Increased Intracranial Pressure Detected by Emergency Ultrasonography of the Optic Nerve Sheath Diameter

ABSTRACT

PURPOSE: A rapid, portable, and noninvasive means of detecting increased intracranial pressure (IICP) is desirable when conventional imaging methods are unavailable. The purpose of this study was to show that ultrasonographic measurement of the optic nerve sheath diameter (ONSD) can accurately predict the presence of IICP. METHODS: We performed a prospective study of emergency department patients suspected of having IICP due to possible focal intracranial pathology. The ONSD was measured 3 mm behind the globe using a linear probe on the closed eyelids of supine patients. For each patient, the mean of the two ONSD measurements was calculated, and the brain computed tomography (CT) was evaluated for signs of IICP. RESULTS: One hundred patients were enrolled; 31 had CT results consistent with IICP, and their mean ONSD was 6.30 mm; the mean ONSD of patients who didn't show signs of IICP on CT was 4.50 mm. The sensitivity and the specificity for the ONSD, when compared with CT results, were 100% and 98.6%, respectively. CONCLUSIONS: The evaluation of the ONSD is a simple noninvasive procedure, and is a potentially useful tool in assessing and monitoring patients suspected of having IICP.